Questions tagged [functions]
Questions about the use of built-in Mathematica functions, including pure functions.
3,309
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I can't find the reason for the flat chart [closed]
That's what I need to do. There is a function
Φ[α,β,z] in which the replacement of k1 and k2 is used. Thus, an
analytical representation of the integral characteristic of the
solution of the problem ...
- 1
5
votes
1
answer
357
views
How to use PlusMinus properly?
As an easy exercise, I would like to define a function
$$f(x)=\pm x$$
and be able to ListPlot the function for some discrete values.
Here is what I tried
...
- 397
1
vote
0
answers
28
views
Efficient construction of a formal polynomial using list manipulations
I have a code which is probably extremely inefficient given my inexperience with Mathematica list manipulation. Take as input data:
...
- 1,287
2
votes
1
answer
103
views
Introduce formal symbols indexed by natural numbers
I'm going to describe a toy example here which I'm hoping with some help, I can then soup up into the more complex application I have in mind.
Suppose the input is a list of lists, and for now take ...
- 1,287
5
votes
1
answer
236
views
Why does this Fourier transform not match the formula?
From this page:
So I'm trying to get that result in Mathematica. From the fourier formula above, we can see that {a, b} = {1,-1}.
However, the code below returns a different result.
...
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1
vote
1
answer
99
views
How to plug in an implicit function into another function and evaluate in Mathematica?
I am wondering how to do the following in Mathematica.
Say, we have an implicit function $y=f(x)$ defined by $F(x,y)=0$.
I would like to evaluate another function $G(x,y)$ at the implicit function $y=...
- 11
4
votes
2
answers
183
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Tropical Operation Conversions: Multiple Operations
I apologize if my syntax is bad. I looked around, but didn't see anything on this in the stack exchange.
I would like to be able to transform a classical real-valued polynomial to a tropical ...
- 143
2
votes
1
answer
90
views
Why Mathematica does not return explicit output [closed]
I am new to Mathematica. One thing that I don't get is why if I define a matrix and give it a name, then use the name in another function, I get back the function itself. However, When I use an ...
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11
votes
1
answer
241
views
4
votes
1
answer
68
views
Replacement, PatternTest, Module related Question
Let's see how MMA handles following type of expression :
Replace[L, {pattTest1->rhs1, pattTest2->rhs2, pattTest3->rhs3}, {1}]
Specific example :
...
- 2,451
0
votes
1
answer
73
views
Animate a point that follows a function inside a plot
I'm trying to create a plot that shows an animation of a point moving along a function. The idea behind this is that a I want the point to follow the function until the discontinuity point.
For every ...
- 69
3
votes
2
answers
84
views
Find global maximum of InterpolatingFunction in interval but not maximum value
I have InterpolatingFunction generated from experimental data with many local maxima, one major peak I need to find, and the tail that grouse much higher then major peak. I tried to find my peak with ...
- 3,199
3
votes
1
answer
78
views
Classifying elements, by the value of a fixed function, using Replace
Let L be a list of several lists. And the length of each list is less than 1000.
You can create L by
...
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1
vote
3
answers
67
views
Module returns multiple functions
I want to write a module that returns two functions which then can be evaluated later on. I know how to do it with a single function, but I don't know how to make it work for multiple functions.
An ...
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1
vote
1
answer
89
views
While inside a function body does not work as expected [closed]
I'm trying to write a function that return a randomly created rational polynomial function that has a discontinuities points.
I already have a function that generates random rational polynomial (...
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1
vote
0
answers
71
views
sometimes Select / sometimes Position is faster
As you see,
For list L,
L1(Select method) is slower than L2(Position method).
But for list <...
- 2,451
0
votes
1
answer
43
views
How to define a function of parameters of a DSolve output?
If I have some ODE that has some parameters, say $a$ and $k$, how would I define a function of those parameters of the solution DSolve.
For example cosider the following code
...
- 101
0
votes
1
answer
48
views
Find the parameter region where function returns negative value
I have a function $f(m,n)$ where m and n are positive integers. Suppose $f(m,n)$ is like a black box, I can get values of it when I enter values of m and n. I want to scan over a region for example $...
- 51
0
votes
0
answers
66
views
Packed/Unpacked array - what object/like 0 or 1?/how to check/ [duplicate]
In Mathematica, there is a concept called packed array.
...
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0
votes
1
answer
32
views
Recursive error encountered when updating rules of assignment [closed]
I'm working on a problem which requires associating a single (complex) number with a pair of binary vectors. I'm doing this by creating a set of assignments through a function I call ...
- 595
3
votes
2
answers
90
views
How to remove duplicates from a pair with some conditions?
Here is a simpler example of my real problem.
Assume that I have a groups which includes sublists as follows:
...
- 2,147
0
votes
0
answers
36
views
Extracting function domain from a finite set of assignments
Suppose we define a function through a finite collection of equalities, e.g.,
f[1] = 1; f[26] = 321
and so on. We can extract the set of output values by running
<...
- 595
2
votes
0
answers
39
views
Delete list item if message is thrown
I have a nested list with each element containing FindRoot like this:
{FindRoot[a,b], FindRoot[c,d], FindRoot[e,f],...}
...
- 147
5
votes
4
answers
181
views
Find shortest distance between two functions [closed]
The problem is to find the shortest distance for given functions: y=x^2+7/2 and y=ln(x) without using Minimize.
Does anyone have any idea how to approach this ...
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9
votes
4
answers
527
views
How can I use variables instead of slots in DeleteCases?
Here is a toy example to illustrate my problem. I have a list of 3-tuples and I want to delete elements from this list that satisfy a condition shown below.
...
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0
votes
0
answers
31
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Using the recursion index to compare with a value in another list
I am trying to generate an arrivals and departures plot for a signalised junction with the following parameters:
lambda: rate of arrival
c: cycle length of traffic lights
g: length of time signal is ...
4
votes
1
answer
122
views
How to get a function from a string?
I'm trying to create a function that takes in input a function written as string and the return it applying a ToExpression and an Evaluate (Code below).
The goal of this function is to transform the ...
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4
votes
3
answers
480
views
6
votes
5
answers
794
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How can I apply a function only to even-index elements of a list?
A = {1, 2, 3, 4, 5}
and, Dd[P_] := P + 1
How can I map "Dd" into "A" such that the outcome is: {1, 3, 3, 5, ...
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3
votes
1
answer
53
views
RunProcess : Save directly to Mathematica Variable
I can convert mysource.jpg to myresult.jpg using an external program myprog.exe, and set a ...
- 2,451
3
votes
1
answer
61
views
Stop NotebookEvaluate before the end of a notebook depending on test inside this notebook
CONTEXT:
Hello,
I have 2 notebooks, lets call them "Main.nb" and "FileProcessing.nb". In my "Main.nb" I have a Do loop where the iterating parameter goes over 300 .csv ...
- 31
2
votes
1
answer
117
views
Speed Up the Gelman-Rubin-History function
A bit of background information
I have created a function to calculate the convergence of the Gelman Rubin diagnostic (useful in Bayesian analysis). The function seems to work as I want, however I ...
- 336
0
votes
1
answer
26
views
Confusing abnormalities observed when counting a specific operator in an expression [duplicate]
Recently I have met with some confusing abnormalities when trying to determine if there is a specific operator (usually Plus[] ) in an expression by programming. ...
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2
votes
1
answer
137
views
A question related to the usage of LegendLayout -> {"Row", 1}
I saw this piece of code from an answer by @Syed here.
...
- 2,147
3
votes
2
answers
190
views
Why is the matrix "mat" not modified here?
Why is the matrix mat not modified here?
I expected it changes with list1 and list2 so that
<...
- 1,750
0
votes
0
answers
28
views
How to combine several similar terms in computation of algebra?
As the title shows, how can I combine several similar terms when I try to compute some complex algebra terms. For example, I want the result of $$\frac{1}{6} b_1 \left(-\left(b_2^2 \left(-2 \sqrt{3} e^...
- 101
0
votes
0
answers
37
views
Eliminate point of function
So I have a function f(x) and I know that for x=x1 the function goes to infinity. I want to remove this point of the function and a "new" function that interpolates from x1- to x1+ at that ...
2
votes
2
answers
143
views
Double quotes as a 'function' (verbatim ToString?)
Can we construct a function F such that F makes any typed text into a string.
Just like double quotes.
...
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0
votes
0
answers
42
views
Non-Gaussian Hidden Markov Process
I'm using estimated process to simulation a Hidden Markov Process with two states using data derived from different ARIMA processes
...
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3
votes
3
answers
255
views
How can I delete duplicates with Abs?
I have this list with some duplicate elements and I want to delete duplicate ones.
...
- 1,750
4
votes
1
answer
103
views
Why is this region in RegionPlot3D wrong?
I believe this is simple, but I can't wrap my head around forming region for RegionPlot3D.
I have been reading and trying to understand how to write the region but ...
- 1,750
1
vote
1
answer
107
views
Why does this TeXForm cause many errors?
Why do I get this error? I don't do any calculation with this. I just want to use TeXForm and then wrap MaTeX around it.
...
- 1,750
5
votes
2
answers
1k
views
Why does this triple integral take so long?
How can I compute this triple integral?
I tried this but it has been running for a long time and not return result yet.
...
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0
votes
0
answers
48
views
Function for probability distribution approximation of a compound random variable
In the book (Klugman et al, 2019) on can see the
Example 9.12. The number of claims has a Poisson–ETNB distribution with
Poisson parameter 𝜆 = 2 and ETNB parameters 𝛽 = 3 and 𝑟 = 0.2. The
claim ...
- 111
2
votes
2
answers
226
views
Three equation solving analytically in Mathematica
Im doing coding in iterative schemes but I do not know to solve three equations analytically in Mathematica step by step. For example I given thre equations in the attached figure. I want to solve ...
- 169
2
votes
1
answer
169
views
Why is this RevolutionPlot3D empty in the middle around x = 0.5?
Why is this RevolutionPlot3D empty in the middle around x = 0.5 like this?
...
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4
votes
1
answer
174
views
How can I fill this region?
How can I fill this region?
Plot[{x^2, x^2 - 2 x + 1}, {x, -2, 2},
PlotRange -> {Automatic, {0, 0.5}}, GridLines -> Automatic]
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1
vote
2
answers
78
views
Ploting a function
I just ploted y[x],y'[x] but I would like to plot other function which is g[x] based on my solution but it can't plot this ??!!
...
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3
votes
3
answers
123
views
How to insert some number of parentheses into an expression to get smallest integer result?
Assume that I have an expression like this (without evaluating)
expr = 1/2/3/4/5/6/7/8/9/10
You can insert some number of parentheses into the expression above to ...
- 2,147
4
votes
1
answer
68
views
Mathematica replaces list of zeros with zero [closed]
Consider the following functions:
f[x_]:= {{Im[x], Re[x]}, {Re[x], Im[x]}};
g[x_]:= {{Im[x],0},{0,0}}
When applying each of the functions to the list of lists <...
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